FIGURE 3 

Simulation results for the system in equation (3). Here, k(t)=0.01(1+sin(t)) with =0.005, k_on=10, k_off=10, =0.01, p_TOT=100, X(0)=5. The choice of protein decay rate (in min^-1) corresponds to a half-life of about 1 h. The frequency of oscillations is chosen to have a period of about 12 times the protein half-life in accordance to what is experimentally observed in the synthetic clock of Atkinson et al (2003). All simulation results were obtained by using MATLAB (Simulink), with variable-step ODE solver ODE23s. The green plot (solid line) represents X(t) originating by the isolated system in equation (2), while the blue plot (dashed line) represents X(t) obtained by the interconnected system of equation (3). Both transient and permanent behaviors are different.